additional gain; extra profit; supplementary income
Refers to an extra benefit or profit beyond what is expected or standard. Often used in economic or business contexts, but can apply to any unexpected additional gain.
I was able to go on a trip thanks to the extra profit from my investments.
この仕事は給料以外にも知識が得られる余禄がある。
This job has the additional gain of acquiring knowledge beyond the salary.
Compound of 余 (extra, surplus) and 禄 (stipend, reward). The exact historical derivation is uncertain, but the kanji combination suggests an additional stipend or reward beyond the regular one.